The present invention relates generally to footwear and apparel, and more specifically to a moisture management system designed to keep the foot and other body parts dry.
The control of moisture or body fluids such as perspiration in shoes has been a problem for many years. Because the foot is enclosed in a shoe, it is difficult for it to breath and evaporate moisture or perspiration that collects against the skin. Many systems have been developed to address the buildup of moisture in a shoe. These systems typically work by absorbing and transporting the moisture away from the foot towards the outside of the shoe to allow for perspiration to evaporate. In many cases, deodorizing materials are added to the shoe to help retard the creation of foul odors.
For example, U.S. Pat. No. 2,869,253 discloses a moisture absorbent and self-ventilating footwear article that is produced from fabrics layered and combined with compressed layers of the interior fibrous structure of the luffa plant that can be molded into shapes. One problem with this product is that the shoes made from these materials are initially stiff to the wearer and require time and walking to become more comfortable to wear.
U.S. Pat. No. 3,627,567 describes a leather-like material and process to produce it that claims having air and moisture permeability, moisture absorptivity, and moisture exhalability equivalent or better than leather. The product claims the ability to move moisture away from the foot in the shoe by strong capillary action but has the problem of rewetting the foot if the shoe does not immediately evaporate all of the liquid, leaving the feeling of a wet foot.
U.S. Pat. No. 4,430,811 presents a multilayered composite structure that is designed to absorb and transport moisture away from the wearer's foot but has the disadvantage of holding much of the moisture in capillaries in the shoe fabric. This allows the fabric to release liquid water when pressure is applied so that it can rewet the foot. A number of other patents disclose similar attempts to move liquid water or perspiration away from the foot through multilayered or interknitted constructions. These references include U.S. Pat. Nos. 4,465,730, 5,217,782, 5,291,617, 5,306,536, 5,365,677, 5,378,529, 5,614,302, 5,746,013, 6,432,504 and U.S. Patent Application Ser. Nos. US2001/0009830 and US2002/0094740.
A number of patents disclose the addition of adsorptive fillers that enhance the ability of a fabric to capture moisture or body fluid and then to hold and gel the fluid to keep it from moving about in the fabric. U.S. Pat. No. 5,763,335 describes a layered composite fabric comprised of multiple layers of fabric and a foam layer made more hydrophilic with the addition of powdered superabsorbent polymer and resistant to odor by the addition of antimicrobial agents directly into the foam as it is produced. This product has the disadvantage of being very heavy, heat-insulative, and expensive to produce for footwear. U.S. Patent Application No. US2002/0128420 describes another foam material that has added into the precurser materials small amounts of powdered absorbent fillers to enhance its moisture management properties but which also has the disadvantages of heavy weight, heat-insulation, and high cost.
U.S. Patent Application No. US2002/0025749 describes a moisture absorptive and dischargeable cloth that comprises a hydrophobic synthetic fiber portion of not less than 60 weight % with moisture highly absorptive and dischargeable organic fine particles that are bonded to the surface of the fiber by graft polymerization. U.S. Pat. No. 5,141,794 describes a multilayered structure including an impervious liquid layer that includes as one of the layers a relatively porous substrate that has been impregnated with a superabsorbent material. The material swells and gel-blocks to prevent liquid pass- through of the product.
U.S. Patent Application No. US2002014898 discloses a method of odor and liquid containment in a disposable absorbent sheet structure. The sheet is heavily treated with odor controlling agents in the absorbent structure. The product is a replaceable shoe insert and as such is not suitable as a permanent component of a shoe upper.
U.S. Pat. No. 4,530,873 discloses a sweat-absorbent textile fabric that comprises a first fabric layer that has high water permeability and low moisture absorption and a second fabric layer that has high moisture absorption substantially higher than the first fabric layer with the two layers being integrally connected together to form a double layered structure. The first fabric layer is constructed of hydrophobic polymer fibers while the second fabric layer comprises hydrophilic polymer fibers with high water retentivity. The fabric layers are constructed in a manner such that the outer water permeable layer is coarser in construction than the inner water absorptive layer. This fabric construction has the disadvantages of not functioning with a mesh appearance for style needs in many applications and allowing water not absorbed by the water absorbent layer to move through capillary action back into the water permeable fabric layer to rewet it.
U.S. Patent Application Nos. US 2002/01074945, US2002/0103469 and U.S. Pat. No. 6,395,957 disclose an absorbent web that has a dry feel produced from papermaking fibers. The absorbent web has hydrophobic matter deposited preferentially on elevated regions of the upper surface of the base sheet in a discontiguous manner. This fabric has the disadvantage of not having the strength characteristics to be suitable for use as a permanent component of footwear.
In view of the above, it can therefore be seen that there is a need for a moisture management system which addresses the shortcomings of the prior art.